1. Field of the Invention
The present invention relates to anhydrous zinc antimonate colloid particles sol coated with a silicon-containing substance and a method for producing the same by adding a silicon-containing substance such as a silane coupling agent, a silylating agent or the like to an aqueous or organic solvent sol of anhydrous zinc antimonate. The anhydrous zinc antimonate sol of the present invention finds application in various fields such as transparent antistatic materials, e.g., resins, plastics, glasses, paper, and magnetic tapes, transparent ultraviolet absorbents, transparent heat ray absorbents, high refractive index hard coating agents, antireflective agents, and the like.
2. Description of Related Art
Japanese Patent Application Laid-open No. 219743/1994 discloses aqueous or organic solvent sols of anhydrous zinc antimonate. The disclosed sols include those aqueous or organic solvent sols of anhydrous zinc antimonate which are stabilized with alkylamines such as ethylamine, propylamine, isopropylamine, and diisobutylamine, alkanolamines such as triethanolamine and monoethanolamine, diamines such as ethylenediamine, hydroxycarboxylic acids such as lactic acid, tartaric acid, malic acid, and citric acid. The organic solvents are alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, glycols such as ethylene glycol and diethylene glycol, cellosolves such as ethylcellosolve and propylcellosolve, amides such as dimethylformamide and dimethylacetamide, and the like.
The organic solvent sols of anhydrous zinc antimonate are used as a transparent antistatic paint, for example, making the best of the characteristics of fine particles. In this case, organic solvent sol of anhydrous zinc antimonate and various resins are mixed to form paints. In order for the mixture to exhibit satisfactory performance as a transparent antistatic paint, the particles of anhydrous zinc antimonate sol must be dispersed in a state close to primary particles without causing their agglomeration. As a solvent for the resins used for this purpose includes hydrophobic solvents such as toluene and xylene, high boiling alcohols such as isopropyl alcohol and butyl alcohol, and the like. Low boiling solvents such as methanol, if present in paints, could cause whitening of coating films due to flushing, so that it is usually preferred that methanol is substituted by one of the above described organic solvent before use. For this reason, the organic solvent sol of anhydrous zinc antimonate for use as a transparent antistatic paint after being mixed with various resins uses hydrophobic solvents such as toluene and xylene or high boiling alcohols such as isopropyl alcohol and butyl alcohol.
However, the anhydrous zinc antimonate organic solvent sols disclosed in Japanese Patent Application Laid-open No. 219743/1994, which are stabilized by addition of alkylamines, alkanolamines, diamines and hydroxycarboxylic acids, exhibit insufficient sol dispersibilities when a high boiling alcohol such as isopropyl alcohol is used as the solvent, so that they have insufficient transparency for use as a transparent antistatic paint.